Cooling of fluids such as for the liquefaction of industrial gases is an important step which is used in many operations. In the case of the liquefaction of industrial gas, typically the industrial gas is liquefied by indirect heat exchange with a refrigerant. Such a system, while working well for providing refrigeration over a relatively small temperature range from ambient, is not as efficient when refrigeration over a large temperature range, such as from ambient to a cryogenic temperature, is required. One way this inefficiency has been addressed is to use a liquefaction scheme with multiple circuits wherein each circuit serves to reduce the temperature of the industrial gas until the requisite cryogenic condensing temperature is reached. However, such multiple circuit industrial gas liquefiers may be complicated to operate.
A conventional single circuit liquefier system is much less complicated than a multiple circuit liquefier but such a system imposes very stringent requirements on the selection of the refrigerant. One way of addressing this inflexibility problem is to use a multicomponent refrigerant fluid instead of the single component refrigerant conventionally used in cooling or liquefying circuits. However, even with the use of a multicomponent refrigerant fluid in a conventional single circuit system , it is difficult to carry out the cooling and/or liquefaction efficiently, especially over a large temperature range, such as from ambient temperature to a cryogenic temperature as would be necessary for the liquefaction of an industrial gas.
Accordingly, it is an object of this invention to provide an improved method for carrying out cooling of a fluid, such as for liquefying an industrial gas, which employs a multicomponent refrigerant fluid.